1. Field of the Invention:
The present invention relates to a reagent delivery device which is preferably used for an automatic chemical analyzer.
2. Description of the Background Art:
In an automatic chemical analyzer, use is made of various kinds of reagents for effecting multi-item analysis. In a known reagent delivery device for delivering plural kinds of reagents, there has been proposed (1) a device having plural pairs of delivery syringes and a delivery nozzle corresponding to respective reagents, (2) a device having one common pair of delivery syringes and a delivery nozzle, which function to selectively deliver a number of reagents by moving the delivery nozzle and (3) a device having a rotary flow-line changing valve which functions to change a plurality of reagent flow-lines one by one, as disclosed in Japanese Patent Laid-open Publication No. 76,764/83.
However, in delivery device (1), since it is necessary to provide a number of delivery syringes corresponding to the number of the reagents, the chemical analyzer including delivery device (1) is liable to be large in size. Moreover, delivery device (2) having one common pair of delivery syringe and nozzle has a drawback in that a syringe moving mechanism is complicated and contamination between reagents is liable to occur. Further, in delivery device (3) using the rotary flow-line changing valve, when the reagent is diluted by a washing liquid serving also as a diluting liquid, the flow-line changing valve can be effectively used without causing contamination between reagents, since the reagent is flows away from the valve by the washing liquid. However, when only reagent is delivered, there a drawback occurs in that reagent delivery becomes impossible, because contamination between reagents is caused due to the washing liquids remaining in the flow-lines from the valve to respective reagent discharging outlets.
Furthermore, in an automatic chemical analyzer, sometimes it is necessary to increase the number of channels i.e. the number of test items. However, in delivery device (1), it is necessary to arrange additional delivery syringes in response to the increase of the reagents, and thus the operation for this additional arrangement becomes extremely troublesome and the chemical analyzer including such a delivery device becomes complicated in construction. Moreover, in delivery device (2), if the reagents are concentrically set in a turntable and the reagent is sucked by the delivery nozzle at a predetermined position, it is easy to deal with the increase of the delivery reagents. However, in this case, there remains a problem of contamination between reagents. Further, in the delivery device (3), if the flow-line changing valve is exchanged, it is easy to accomodate the increase of reagents, but the valve exchanging operation is extremely troublesome and a chemical analyzer including such a delivery device becomes complicated in construction.